Shopsmith Forums

I have a mark 5 that I purchased in which the switch was bad. The machine would run for a few seconds and turn off. I replaced the switch and the switch works and the machine runs until I put the motor back in the case with the switch connected to the headstock. The unit now causes the breaker to flip even if belts are not attached.

So it runs fine until the switch is attached to the headstock. It runs with or without the belts attached, and runs with the belts if the switch is not connected to the headstock.

Has anyone had a similar issue and if so how did you correct the short?

If you have an ohmmeter or an idiot light(continuity tester) see if a switch terminal is shorted to the mounting threads.

brbdogsonfire wrote: Mon Jan 10, 2022 12:39 pm I have a mark 5 that I purchased in which the switch was bad. The machine would run for a few seconds and turn off. I replaced the switch and the switch works and the machine runs until I put the motor back in the case with the switch connected to the headstock. The unit now causes the breaker to flip even if belts are not attached.

So it runs fine until the switch is attached to the headstock. It runs with or without the belts attached, and runs with the belts if the switch is not connected to the headstock.

Has anyone had a similar issue and if so how did you correct the short?

Possibly a short inside the switch, most likely between hot and switch chassis.(?) I think that is only possible on "A" or "B" headstocks with the toggle switch. That could result in the symptoms you describe, but could be dangerous to use the switch uninstalled. Please clarify headstock version, whether it is grounded, and where it is grounded if known. Also if it is a standard circuit breaker that is tripping, as opposed to Ground Fault and/or Arc Fault types.

(In a typical Mark 5/V the power cord ground is directly connected to the motor, so the rest of the machine is grounded when the motor in in the pan and the pan is installed. But early models weren't grounded, so there are multiple grounding schemes possible.)

- David